1. Field of the Invention
This invention relates generally to printing media roll holders for computer driven printer/plotters of the type that produce engineering or other large drawings on paper, vellum, film or other printing media which is drawn through the mechanism from a roll, and more particularly to an auxiliary printing media roll holder for attachment to such printer/plotters to accomodate large rolls of feed printing media and increase the printing/plotting capacity and operational efficiency and reduce downtime due to reloading feed printing media rolls.
2. Brief Description of the Prior Art
Commercially available inkjet printers and plotters have a built-in feed paper roller which is contained in a housing at the front end of the machine on which the printing media is wound. Many popular printer/plotters, such as the Hewlett-Packard HP DesignJet 350 series are designed for low end use and may be supported on a desk for feeding individual sheets of paper and other sheet media or may be supported on an accessory roll-feed and legs unit which has a housing that contains a roll of feed media (150 linear feet) for continuous plotting. Larger printer/plotters, such as the Hewlett-Packard HP DesignJet 650, 750, and 2500 series are designed for high end use, and the roll-feed and legs unit is a standard component of the printer/plotter.
Due to the size constraints of the cabinet or the housing of the roll-feed and legs unit, the diameter of the roll and thus the length of the paper available for use is limited. Most of these printers and plotters, and the feed-roll housing are sized to accomodate a 150 foot roll of feed paper which is approximately 3" in diameter, depending upon the type of paper. While the 150 foot roll of feed paper may be adequate for low end use or for a small business, it is not satisfactory for many larger users.
Although the manufacturers of printers and plotters have attempted to improve the duty cycle, and reduce down-time, they have done so by merely providing larger capacity ink cartridges to increase the ink reservoir so that the user does not run out of ink. Currently, the user will usually run out of paper before depleting the ink supply. For example, the ink supply may be capable of printing or plotting 3,000 linear feet, while the maximum feed paper supply is only be 150 linear feet.
For a user to complete a large plotting job, it may be necessary to replace the roll of feed paper or other media many times before the job is completed. For example, if the printer/plotter has an ink cartridge with a capability of plotting 3,000 linear feet and a 150 foot roll of feed paper, the user must replace the paper roll 20 times before running out of ink, depending of course upon the DPI (dots per inch) of the plotting task.
Loading a new roll of feed paper or other media is not a simple operation, because the paper roll is not simply replaced, the edges of the paper must be precisely re-aligned and the printer/plotter may have to be reset and re-calibrated to recognize the placement of the new paper. With larger printer/plotters, such as the Hewlett-Packard 750 series, re-calibration takes about 10 minutes, and with the HP 2500 series it takes even longer. Thus, excessive down-time and many man hours must be spent merely to reload the feed paper. Some large companies do their plotting jobs in the evenings, and must pay an employee to be present just to reload the feed paper.
In a preferred embodiment the present auxiliary paper roll holder accomodates a 500 foot roll of feed paper. Tests have shown that a Hewlett-Packard 750 series printer/plotter equipped with the present auliliary paper roll holder supporting a 500 foot roll of feed paper will allow the printer/plotter to operate continuously for about 9 hours before requiring a new roll of paper, whereas, the same machine utilizing its existing 150 foot feed paper supply will only operate for about 2 hours and 45 minutes before requiring a new roll of paper. Thus, the auxiliary paper roll holder eliminates 3 shut-down and paper roll change operations to accomplish the same plotting task. The present paper roll holder will allow a user to operate the machine all day or all evening, unattended, to complete large plotting jobs without interruption or down-time.
There are several patents which disclose printers and plotters having a built-in feed paper roller housed in the cabinet of the machine or mounted in an accessory roll-feed and legs kit, and various paper roll holding devices.
Kline et al, U.S. Pat. Nos. 5,363,129 and 5,530,459, assigned to Hewlett-Packard Company, disclose retractable pinch roller feeding and retaining mechanisms which are contained within the chassis of a computer driven printer/plotter of the prior art type discussed above which is supported on a roll-feed and leg unit and has a roll of print media contained inside an arcuate housing at the upper end of the legs, and a U-shaped wire frame paper catcher between the legs that receives the print media as it exits the machine. As discussed above, due to the size constraints of the chassis or housing of the roll feed unit, the diameter of the roll and thus the length of the paper available for use is limited. The present invention is suitable for installation between the support legs of this type of printer/plotter to accomodate a secondary large feed roll of printing media and increase its printing/plotting capacity and operational efficiency and reduce downtime due to reloading the print media rolls contained within the housing, and also to support its existing paper catcher, without modification to the printer/plotter chassis or support leg unit.
Stein, U.S. Pat. No. 5,632,455 discloses a wide-bed plotter supported laterally spaced legs and has a media supply roll and a media take-up roll at the longitudinal sides rotatably mounted at opposed ends inside a housing. The supply and take-up rolls have flanged cylindrical hubs at their outer ends with an inside diameter smaller than the inside diameter of the smallest roll core expected to be supported and a rough surface for rolling engagement with a portion of the inside diameter of the core.
Oda, U.S. Pat. No. 5,327,168 discloses a rolled sheet conveying and route control apparatus for plotters supported between laterally spaced legs that has a media supply roll and a pair of tension rollers to impart weak tension to the print media to prevent snaking, and a manually adjustable threaded mechanism on the tension roller support for adjusting the slant of the rollers to control and equalize the distances of the left and right edges of the print media between the tension rollers and the drive roller.
Poehlein, U.S. Pat. No. 4,821,974 discloses a media supply roll for a large document printer having two end support hubs with compressible springs mounted on opposed axially aligned spindle shafts. The media roll core is seated on tapered surfaces of the hubs and the compression spring allows one end to be urged outward so that, once fully seated against the hub member, one spring predominates and maintains the roll in a precisely aligned axial position.
Buzzell, U.S. Pat. No. 4,277,034 discloses a paper roll holder with a dancer bar for use with printers. An axle is inserted through the core of the supply roll an rotatably supported in a bracket. The paper extends from the supply roll over a resiliently-mounted dancer bar and into the printer.
The present invention is distinguished over the prior art in general, and these patents in particular by an auxiliary printing media roll holder use with printer/plotters to accomodate a large feed roll of printing media and increase the printing/plotting capacity and operational efficiency of the printer/plotter and reduce downtime due to reloading printing media rolls. The auxiliary roll holder has an elongate longitudinal frame with opposed ends adapted to be mounted between the laterally spaced legs that support the printer/plotter, longitudinal rollers rotatably mounted on the frame in parallel spaced relation, a longitudinal spindle bar removably received and rotatably engaged at opposed ends on the frame, and a pair of hubs slidably received and releasably secured on the spindle bar near its opposed ends, each having a generally cylindrical core receiving portion disposed in opposed facing relation for engaging and supporting opposed ends of a tubular core of a large roll of printing media which is drawn from the roll, passes over the roller, and into the printer/plotter. A weight bar engages the printing media and applies and maintains tension on the printing media to keep it taut and prevent it from unrolling when feeding stops and as resistance of the rolled printing media becomes lighter as it reaches the end of the roll. The auxiliary printing media roll holder also receives and supports a paper catcher that receives the printing media as it exits the printer/plotter. In a preferred embodiment the auxiliary roll holder will acomodate a 500 linear foot roll of printing media.